Internal combustion engines are a vital part of modern society. Since development of the internal combustion engine, many internal-combustion-engine-based industries, such as the automobile industry, have devoted enormous amounts of money and resources toward research and development of various ways to increase the useful work realized from a given amount of fuel, or fuel efficiency. Designers and manufacturers of internal combustion engines have improved the fuel efficiency of internal combustion engines, and have improved the fuel used in internal combustion engines.
Internal combustion engines generally operate by combusting various hydrocarbon-based fuels that are refined from crude oil. Crude oil is believed to be a fossil fuel that is formed from plants and animals that once lived in ancient seas and that have decayed into hydrocarbons of various sizes and structures. Crude oil is refined and chemically processed into many different petroleum-based products, including: gasoline, diesel fuel, kerosene, jet fuel, lubricating oil, gas oil, plastics and other polymers, asphalt, and wax.
Crude oil refining, in part, consists of separating variable-sized hydrocarbons into fractions, each fraction containing similarly-sized hydrocarbons within a narrow range of volatility. Hydrocarbons contain potential energy that is released during the internal combustion process within internal combustion engines. The fuel efficiency of current internal combustion engines remains significantly below the theoretical, thermodynamic maximum obtainable efficiency. Designers, manufacturers, and consumers of internal combustion engines have, therefore, recognized the need for further improvements to internal combustion engines and fuel in order to increase the fuel efficiency of internal combustion engines.